Automatically update the entity propery when a member created, updated or deleted

homeassistant/components/mqtt/entity.py

@@ -33,7 +33,13 @@ from homeassistant.const import (
     CONF_URL,
     CONF_VALUE_TEMPLATE,
 )
-from homeassistant.core import Event, HassJobType, HomeAssistant, callback
+from homeassistant.core import (
+    CALLBACK_TYPE,
+    Event,
+    HassJobType,
+    HomeAssistant,
+    callback,
+)
 from homeassistant.helpers import device_registry as dr, entity_registry as er
 from homeassistant.helpers.device_registry import (
     DeviceEntry,
@@ -476,12 +482,41 @@ class MqttAttributesMixin(Entity):
         [MessageCallbackType, set[str] | None, ReceiveMessage], None
     ]
     _process_update_extra_state_attributes: Callable[[dict[str, Any]], None]
+    _monitor_member_updates_callback: CALLBACK_TYPE
 
     def __init__(self, config: ConfigType) -> None:
         """Initialize the JSON attributes mixin."""
         self._attributes_sub_state: dict[str, EntitySubscription] = {}
         self._attributes_config = config
 
+    def _monitor_member_updates(self) -> None:
+        """Update the group members if the entity registry is updated."""
+        entity_registry = er.async_get(self.hass)
+
+        async def _handle_entity_registry_updated(event: Event[Any]) -> None:
+            """Handle registry update event."""
+            if (
+                event.data["action"] in {"create", "update"}
+                and (entry := entity_registry.async_get(event.data["entity_id"]))
+                and entry.unique_id in self._attributes_config[CONF_GROUP]
+            ) or (
+                event.data["action"] == "remove"
+                and self._group_entity_ids is not None
+                and event.data["entity_id"] in self._group_entity_ids
+            ):
+                self._update_group_entity_ids()
+                self._attr_extra_state_attributes[ATTR_ENTITY_ID] = (
+                    self._group_entity_ids
+                )
+                self.async_write_ha_state()
+
+        self.async_on_remove(
+            self.hass.bus.async_listen(
+                er.EVENT_ENTITY_REGISTRY_UPDATED,
+                _handle_entity_registry_updated,
+            )
+        )
+
     def _update_group_entity_ids(self) -> None:
         """Set the entity_id property if the entity represents a group of entities.
 
@@ -506,6 +541,7 @@ class MqttAttributesMixin(Entity):
         await super().async_added_to_hass()
         self._update_group_entity_ids()
         if self._group_entity_ids is not None:
+            self._monitor_member_updates()
             self._attr_extra_state_attributes = {ATTR_ENTITY_ID: self._group_entity_ids}
 
         self._attributes_prepare_subscribe_topics()

tests/components/mqtt/test_light_json.py

@@ -101,6 +101,7 @@ from homeassistant.const import (
     STATE_UNKNOWN,
 )
 from homeassistant.core import HomeAssistant, State
+from homeassistant.helpers import entity_registry as er
 from homeassistant.util.json import json_loads
 
 from .common import (
@@ -1893,7 +1894,7 @@ async def test_white_scale(
     assert state.attributes.get("brightness") == 129
 
 
-async def test_light_group_discovery_members(
+async def test_light_group_discovery_members_before_group(
     hass: HomeAssistant, mqtt_mock_entry: MqttMockHAClientGenerator
 ) -> None:
     """Test the discovery of a light group and linked entity IDs.
@@ -1919,6 +1920,62 @@ async def test_light_group_discovery_members(
     assert group_state.attributes.get("icon") == "mdi:lightbulb-group"
 
 
+async def test_light_group_discovery_group_before_members(
+    hass: HomeAssistant,
+    mqtt_mock_entry: MqttMockHAClientGenerator,
+    entity_registry: er.EntityRegistry,
+) -> None:
+    """Test the discovery of a light group and linked entity IDs.
+
+    The group is discovered first, so the group members are
+    not (all) known yet in the entity registry.
+    The entity property should be updates as soon as member entities
+    are discovered, updated or removed.
+    """
+    await mqtt_mock_entry()
+
+    # Discover group
+    async_fire_mqtt_message(hass, GROUP_TOPIC, GROUP_DISCOVERY_LIGHT_GROUP_CONFIG)
+    await hass.async_block_till_done()
+
+    # Discover light group members
+    async_fire_mqtt_message(hass, GROUP_MEMBER_1_TOPIC, GROUP_DISCOVERY_MEMBER_1_CONFIG)
+    async_fire_mqtt_message(hass, GROUP_MEMBER_2_TOPIC, GROUP_DISCOVERY_MEMBER_2_CONFIG)
+
+    await hass.async_block_till_done()
+
+    assert hass.states.get("light.member1") is not None
+    assert hass.states.get("light.member2") is not None
+
+    group_state = hass.states.get("light.group")
+    assert group_state is not None
+    assert group_state.attributes.get("entity_id") == ["light.member1", "light.member2"]
+    assert group_state.attributes.get("icon") == "mdi:lightbulb-group"
+
+    # Remove member 1
+    async_fire_mqtt_message(hass, GROUP_MEMBER_1_TOPIC, "")
+
+    await hass.async_block_till_done()
+
+    assert hass.states.get("light.member1") is None
+    assert hass.states.get("light.member2") is not None
+
+    group_state = hass.states.get("light.group")
+    assert group_state is not None
+    assert group_state.attributes.get("entity_id") == ["light.member2"]
+
+    # Rename member 2
+    entity_registry.async_update_entity(
+        "light.member2", new_entity_id="light.member2_updated"
+    )
+
+    await hass.async_block_till_done()
+
+    group_state = hass.states.get("light.group")
+    assert group_state is not None
+    assert group_state.attributes.get("entity_id") == ["light.member2_updated"]
+
+
 @pytest.mark.parametrize(
     "hass_config",
     [